The most widely used thiolcarbamate derivatives are the N-N-diisobutyl-S-ethyl thiolcarbamate (Butilate), the N,N-di(n-propyl)-S-ethyl thiolcarbamate (EPTC), the N,N-di(n-propyl)-S-(n-propyl)thiolcarbamate (Vernolate), the N,N-diethyl-S-ethyl thiolcarbamate (Ethiolate), the N-ethyl-N-butyl-S-ethyl thiolcarbamate (Pebulat), the N-ethyl-N-cyclohexyl-S-ethyl thiolcarbamate (Cikloat) and N,N-hexamethylene-S-ethyl thiolcarbamate. (Molinat).
Similarly, the chloroacetanilides of the formula IV are also widely used. In the formula IV
The most widely used chloroacetanilide derivatives for controlling monocotyledonous weeds are the 2-chloro-N-isopropylacetanilide (Propachlor), the 2-chloro-2',6-diethyl-N-(methoxymethyl)acetanilide (Alachlor), the 2-chloro-2'-methyl-6'-ethyl-N-(ethoxymethyl)acetanilide (Acetochlor) and the 2-chloro-2',6'-diethyl-N-(buthoxymethyl)acetanilide (Butachlor).
But both types of these two active ingredients have the disadvantage that their effective amount for controlling monocotyledonous weeds also damages the cultivated plant to be protected, that is, they are phytotoxic, therefore these compounds have a decreased applicability. Otherwise, if they are used in such an amount which is not phytotoxic for the cultivated plant, their herbicidal activity is substantially diminished.
Some two decades ago Hoffman discovered that there are compounds as, for example, the 1,8-naphthalic acid anhydride derivatives which decrease the phytotoxic effect of these compounds, i.e. there exist compounds which counteract the damaging effect of the thiolcarbamates when applied together with the thiolcarbamates.
Since then multilateral search was conducted in order to find compounds of antidote effect and such antidote compositions are referred to in countless patent specifications.
For example, the Hungarian patent specification No. 165,736 reports on the antidote effect of compounds of dichloroacetamide type, from which the N,N-diallyl-2,2-dichloroacetamide (R-25,788) is now the most widely used in practice.
The Hungarian patent specification No. 168,977 describes oxazolidine and thiazolidine type antidotes, the Hungarian patent specification No. 170,214 refers to thiazolidine sulphoxide type antidotes, the Hungarian patent specification No. 173,755 reports on antidotes of sulphide-type, the Hungarian patent specification No. 176,867 describes oxazolidine derivatives, the Hungarian patent specification No. 179,643 reports on N-(benzoylsulphonyl)-carbamate, the Hungarian patent specification No. 180,069 refers to N-(benzoylsulphonyl)-thiolcarbamate, while the Hungarian patent specification No. 180,068 describes 2,3-dibromopropionamide derivatives as antidotes.
The Hungarian patent specifications No. 176,458 and 176,784 disclose dichloroacetamide type antidotes as well.
The Hungarian patent specification Nos. 176,669, 176,796, 178,883, 178,892, 178,985, 179,092 and 179,093 report on the antidote effect of dicarboxylic acid derivatives of different structure from the above-cited dichloroacetamide derivatives.
The great number of the patent specifications show that, in spite of the wide search, nobody has managed to find compounds which could be generally used in the protection of cultivated plants against the damaging effect of certain herbicidally active agents. This fact is also supported by the failure of the searches directed to the revelation of the mechanism of the antidote effect. Namely, the researchers do not assume a uniform attitude concerning the biochemical reactions when the antidote is added to the herbicide and the influence of the antidote compounds on the processes brought about by the herbicidal compounds in the cultivated plants. The environmental constituents (e.g. temperature, humidity and pH of the soil) exerting an influence on the plants simultaneously with the effect of the herbicides used for the treatment and the physical properties (vapour pressure, solubility in water) of the herbicidally active agents multilaterally and diversely influence the damaging effect of the herbicides.